An agricultural seeding machine such as a row crop planter or grain drill places seeds at a desired depth within a plurality of parallel seed trenches formed in soil. In the case of a row crop planter, a plurality of row crop units are typically ground driven using wheels, shafts, sprockets, transfer cases, chains and the like. Each row crop unit has a frame which is moveably coupled with a tool bar. The frame may carry a main seed hopper, herbicide hopper, insecticide hopper, trench opener/closer, or other equipment.
One type of opener/closer arrangement uses a depth gauge wheel which is placed ahead of the leading edge of a single disc opener assembly including a seed tube on the trailing side of the disc. The wheel provides depth adjustment, cleans the leading face of the disc, and limits soil lifting and throw adjacent the disc. One or more closing wheels trail the disc to move soil and close the trench over the material deposited from the seed tube. Such openers limit soil disturbance, but often a portion of the seed boot or runner operates soil just outside the seed trench which increases soil disturbance, power requirements, wear, and seed placement inconsistencies. The leading side wheel axis is close to the disc hub so the wheel operates forward of the area where the disc exits the soil. Soil lift at the exit point can be a problem, particularly when the operating depth of the disc is increased. If the boot lies outside the trench, tracking problems are also increased.
With a single disc opener arrangement of this type, the closing wheels trail the seed boot a substantial distance. The actual closing of the trench occurs sometime after the deposited seed reaches the bottom of the trench. As a result, the deposited seed has time to bounce from the bottom of the trench, and this may lead to the seed being placed shallower than desired. At times, the deposited seed can actually bounce completely out of the trench and lie on top of the ground. Seeds which lie on top of the ground will not germinate.
There is a need for a trench opener/closer for an agricultural seeding machine, moving at high ground speeds, which more effectively opens a trench, plants seeds within the trench at the appropriate depth, and closes the trench.